Add support for retrieving listening address of websocket Server

[michaelbeaumont]

It's still a little cumbersome to use because Start() blocks but this makes it possible to use 0 as the port and let the system pick a port then later see which port was chosen, useful for testing.

[lorenzodonini]

I like the idea of splitting the listen and serve up.

I recently added some "hacky" tests on the errors channel, for increasing coverage. I'll quickly investigate where exactly they are breaking and suggest a solution to the failing test.

[lorenzodonini]

It's still a little cumbersome to use because Start() blocks but this makes it possible to use 0 as the port and let the system pick a port then later see which port was chosen, useful for testing.

You could also modify the Start to accept the full listen address (i.e. :8080). That way, you're not just limited to the port. Just an idea.

[michaelbeaumont]

Yeah, I was going to add that separately but changing the listening IP is useful too. But unrelated to setting port to 0, right?

[lorenzodonini]

Yeah, I was going to add that separately but changing the listening IP is useful too. But unrelated to setting port to 0, right?

Yes, it's unrelated. Feel free to add it in a follow-up MR. It would be a breaking change as well, so no rush.